<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

	<link rel="stylesheet" type="text/css" href="css/pid-toolbar.css" >
 <script src="./jquery.min.js"></script>
	<style>
        * {
            margin:0;
            padding:0;
        }
       
		.div-relative{position:relative; color:#000; border:1px solid #000; width:500px; height:400px;background:#111;} 
		.div-a{ position:absolute; left:30px; top:30px; background:#F00; width:200px; height:100px} 
		/* css注释说明： 背景为红色 */ 
		.div-b{ position:absolute; left:50px; top:60px; background:#FF0; width:400px; height:200px} 
		/* 背景为黄色 */ 
		.div-c{ position:absolute; left:80px; top:80px; background:#00F; width:300px; height:300px} 
		/* DIV背景颜色为蓝色 */ 
    </style>
</head>
<body style="margin:50px;">

	<div class="div-relative"> 
		<div class="div-a">我背景为红色</div> 
		<div class="div-b">我背景为黄色</div> 
		<div class="div-c">我背景为蓝色</div> 
	</div> 
</body>
<script>

</script>
</html>